Method and apparatus for forming tubular electric lamps and similar devices



Dec. 3, 1963 w. H. WILLIS ETAL METHOD AND APPARATUS FOR FORMING TUBULAR ELECTRIC LAMPS AND SIMILAR DEVICES 2 Sheets-Sheet 1 Filed June 19, 1958 lnveni'ovs'. WinlieLd H. WiLLis,

Haw-r9 L. Louden, b Robgr t N. I/aLm,

'l'ei? 64 50 neg.

Dec. 3, 1963 w. H. WILLIS ETAL 3,113,010

METHOD AND APPARATUS FOR FORMING TU ULAR ELECTRIC LAMPS AND SIMILAR DEVICES 2 Sheets Sheet 2 Filed June 19, 1958 lnven tovs'. 'W'iWFieLd H.Wil,l,is, "Havv LLOuden, RobeY- c NMaLm,

United States Patent Oflice 3,1 ld-dll h Patented Dec. 3, 1963 f lfifiltl METEQD AND APIPARATU FSR FDRMENG TUBU- LAR ELECEREfi LAMPS AND SiMLLAR DEVHZES Winfield H. Willis, B adford, Harry ll... London, Cleve land, and Robert N. Mains, Willoughhy, @hio, assignors if? general Electric (lornpany, a corporation of New oru Filed June 19, 1958, Ser. No. 743,192 7 Claims. (@l. 65-54) This invention relates to method and apparatus for forming electrical devices such as incandescent lamps and glow discharge devices having internal elements such as a filament or electrodes sealed Within a tubular glass envelope particularly of small size.

Certain miniature type glow lamps or discharge devices such as those commercially designated as the NE-Z series are conventionally made from an open glass tube one end of which is sea-led around one or more lead-in wires attached to the internal elements or electrodes of the device and an intermediate portion of which is heated to a plastic state and drawn or stretched to attenuate it and thereby form a constricted section of anticlastic shape which, after evacuation of the envelope or tube through the remaining open end thereof and introduction of the customary filling thereinto, is then tipped-off to hermetically seal the portion of the glass tube in which the internal elements are sealed. Because of the extended length of the attenuation or constriction which is formed in the glass tube by the aboveamentioned stretching operation, such a method of lamp manufacture results in the formation of relatively long and stringy exhaust tips on the envelope of the glow lamp or other device. Such long and stringy exhaust tips are objectionable not only in those glow lamp applications where, because of space limitations, the glow lamp must be of the shortest possible overall length, but also because they limit the permissible length of the electrodes which can be mounted in the envelope without touching the attenuated top end wall thereof. In addition, such long and stringy exhaust tips limit the amount of end-on light from the glow lamp and also present a poor appearance.

it is an object, therefore, of our invention to provide a novel method of making a tubular type glow discharge lamp or similar device of the character referred to having a short rounded top end with a small centralized exhaust tip instead of the heretofore customary long tapering top end and exhaust tip.

Another object of our invention is to provide a novel method of mahin' a tubular type glow discharge device of the character referred to which will permit the use of appreciably longer wire type electrodes for the same total overall length of envelope used heretofore, or alternatively will permit the use of an appreciably shorter overall length envelope for the same length of electrodes used heretofore.

Still another object of our invention is to provide apparatus for automatically making, from open ended glass tubes, tubular type glow discharge lamps or similar devices of the character referred to having short rounded top ends with small centralized exhaust tips projecting therefrom.

Briefly stated, accordance with one aspect of the invention, the intermediate portion of the glass tube, immediately following the attenuation thereof to fonm the customary constriction therein of anticlastic shape, and preferably while the glass of the said constricted section is still in a plastic state from the attenuation thereof, is reshaped or molded to further reduce the diameter of, and form a short well-rounded shoulder in that portion of the constricted section nearest the portion of the glass tube which is to ultimately form the envelope of the device.

in accordance with a further aspect of the invention, means comprising a split-mold are provided to close around that portion of the constricted section of the glass tube which is to be reshaped and to then move axially of the glass tube, in a direction toward the portion thereof which is to form the envelope of the device and while the opposite ends or" the tube are fixedly held, to thereby reduce the diameter of, and in addition upset the plastic glass wall of the said portion of the tube constriction to reshape it into a short well-rounded shoulder on the glass tube.

Further objects and advantages of our invention will appear from the following detailed description of a species thereof and from the accompanying drawings.

In the drawing,

FIG. 1 is a fragmentary plan view, partly broken away and on a reduced scale, of apparatus according to the invention for automatically making tabulated glass envelope assemblies for tubular electric lamps or discharge devices having rounded top ends with small exhaust tips.

FIG. 2 is an elevation, partly in section, of the apparatus comprising our invention and showing the mechanism at the glass tube reshaping station of the apparatus together with the associated means for supporting the glass tube in sealing relation to the leading-in wires which carry the internal elements of the electric lamp or discharge device.

FlG. 3 is a fragmentary perspective view of the operating mechanism for actuating the glass tube reshaping mechanism of the apparatus comprising our invention.

FIGS. 4 to 10 are views illustrating the successive steps for making a glow lamp or similar device in accordance with the method comprising our invention, and

FIG. 11 is an elevation of a completed glow lamp made by the method and apparatus comprising our invention.

Referring to the drawing, the invention is there illustrated in connection with the manufacture of a tubular glow lamp or discharge device of the miniature type such as that commercially designated as the NE-Z series and comprising a small tubular glass envelope 1 formed at one end with. a flattened stem press 2 through which are sealed a pair of leading-in wires 3. Mounted within the glass envelope 1 and formed as extensions of the leadingin wires 3 are a pair of straight wire-type cold electrodes which extend parallel to one another and are formed of a suitable electrode material such as nickel wire, for instance. The envelope 1 contains a filling of a suitable rare gas such as neon or argon or mixtures thereof at a relatively low pressure of, for example, from 20' to 20% millimeters of mercury. During the manufacture of the glow lamp, the envelope 1 is exhausted and the rare gas filling then introduced through a glass exhaust tubulation extending from the end of the envelope opposite the stem press end thereof, which exhaust tribulation is then tipped off to form the exhaust tip 5, thereby hermetically sealing the envelope. Although specifically illustrated in connection with the manufacture of glow lamps, it will be understood that the invention is applicable as well to the manufacture of other simflar types of electrical devices such as miniature incandescent lamps and types of gaseous discharge devices other than that illustrated herein.

The manufacture, in accordance with the invention, of a miniature tubular type glow lamp or discharge device such as described above is carried out with apparatus essentially of the general type conventionally employed heretofore for the manufacture of such type glow lamps and comprising a horizontally arranged turret 6 mounted for intermittent rotational or indexing movement on a vertical shaft (not shown) and provided, around its periphery, with a plurality of similar worksupporting heads 7 which are moved through a closed circular path and indexed, in succession, to a plurality of Work stations. The intermittent rotational index movement of the turret 6 may be imparted thereto by conventional type indexing means (not shown) such as that illustrated, for example, in Stiles et al. Patent 1,742,153 dated December 31, 1929, and comprising, in general, a barrel cam mounted on the main motor-driven drive or cam shaft (FIG. 3) 8 of the machine and engaging with rollers carried by a plate which is fastened to the vertical shaft on which the turret is mounted.

The work-supporting heads 7 are each arranged to hold and support a straight open-ended glass tube 9 and a pair of electrode-carrying leading-in wires 3 in proper assembled relation for sealing together, with the glass tube 9 supported in a vertically extending position with its open lower end placed over and surrounding the leading-in wires which are suported in a vertically extending position with their electrode ends 4 uppermost so as to be located entirely within the lower end portion of the glass tube. For this purpose, each head 7 is provided with two pairs of spring-loaded tube-holding jaws comprising a vertically fixed lower pair of jaws 10 and a vertically movable upper pair of jaws 11. Both of the pairs of jaws 1t and 11 are pivotally mounted to swing in a horizontal plane, and they are normally held in closed position, so as to grip the glass tube 9 therebetween, by the force of tension coil springs 12 and 13, respectively. The lower pair of jaws 10 are carried at the outer ends of a pair of jaw arms 14 which extend in a direction generally radially outward from the periphery of the turret 6 and are pivotally mounted on respective vertical pivot pins 15 which are supported in a mounting bracket 16 fixedly attached to the turret 6. The lower jaws 10 are opened against the force of the spring 12, to permit insertion of the glass tube 9 between the jaws, by a cranktype operating mechanism comprising a collar 17, which is rotatably mounted on a vertical operating shaft 18 supported on the head bracket 16 and is connected by a pair of connecting links 19 to the jaw arms 14. The operating shaft 13 is provided at its lower end with a lever arm 20 carrying a roller 21 which, during the index movements of each head 7 to the unloading station of the machine and continuing up to the glass tube loading station thereof, engages with a stationary cam track (not shown) mounted on a stationary portion of the apparatus, to thereby effect the opening of the jaws 10 and maintain them in open position during the said index movements of each head 7. At the glass tube loading station of the machine, the roller 21 is engaged by separate cam-actuated means at said station for maintaining the lower jaws It in open position thereat to permit insertion of the glass tube 9 therebetween, and for subsequently closing the jaws 10 against the tube 9 to grip it and hold it in place while the head 7 is still positioned at the tube-loading station.

The upper pair of jaws 11, like the lower pair of jaws 10, are also carried at the outer ends of respective jaw arms 22 which extend in a direction generally radially outward from the periphery of the turret and are pivotally mounted on respective pivot pins 23 mounted in a vertically movable upper head bracket 24. The upper head bracket 24 is mounted for vertical sliding movement on a pair of vertical guide posts 25 and 26 upstanding from the lower head bracket 16. The upper head bracket 24 and its associated pair of jaws 11 are normally located in a lowered position, from the time each head 7 is located at the first lead-in wire or weld loading station of the machine up until it reaches the last station (designated C in FIG. 1) before the stretching and attenuation of the glass tube 9, by the engagement of the end faces 27 and 28 of the guide post bearings 29 and St) on the upper and lower brackets 24 and 16, respectively. During the course of index movement of each head 7 from stations C to D, a roller 31 mounted on a post 32 upstanding from the upper head bracket 24 engages and rides up a rise portion 33 of a stationary cam track 34, fixedly mounted on a stationary portion 70 of the machine, to thereby raise the upper head bracket 24 and the associated pair of upper jaws 11 to their uppermost or elevatedposition, thereby stretching and drawing out the heated and softened intermediate portion of the glass tube 9 so as to form an attenuation or constriction therein of anticlastic shape. Following the elevation of the head bracket 24 and the associated upper pair of jaws 11 to their raised position during the course of travel of each head 7 from station C to D, the said upper head bracket 24 and the associated jaws 11 then remain in such elevated position until their subsequent index movement to the first lead-in wire or weld loading station of the machine during which index they then move down and return to their normal lowered position by the disengagement of the roller 31 from the end of the underlying cam track 34 and the subsequent push-down of the roller 31 and upper head bracket 24 by an upper stationary spring-loaded cam track (not shown). The upper set of jaws 11 are opened and closed, in the same manner as the lower jaws 10, by a crank-type operating mechanism similar to the operating mechanism for the lower jaws 1t) and comprising a collar 35 fixedly secured to the vertical operating shaft 13 and connected by a pair of connecting links 36 to the jaw arms 22 which carry the upper jaws 11.

In addition to being provided with the lower and upper pairs of tube-holding jaws 1t) and 11, each head 7 is also provided with suitable holder means 37 for supporting the two leading-in wires 3 with their electrode extensions 4 in proper sealing relation to the glass tube 9 held in the jaws 10 and 11. The said holder means 37 is in the genenal form of a holder block or so-called weld pocket member which is provided with a pair of upwardlyopening vertical passageways or pockets 38 for accommodating therein the electrode-carrying leading-in wires 4 or welds and positioning them with their electrode ends 4 uppermost and located within the lower end portion of the glass tube 9 held in the lower and upper jaws 10 and 11. The holder block or weld pocket member 37 is preferably split vertically, through the center plane of the two vertically extending weld pockets 38 (which center plane is disposed radially of the turret 6), into two halfsections 39 which are arranged to be separated in order to permit clean-out of the weld pockets 38 of any foreign matter therein. For such purpose, the two half-sections 39 constituting the weld pocket member 37 are pivotally mounted for horizontal swinging movement on respective vertical openating shafts 4-0 which are rotatably mounted in a bearing support bracket 41 fastened to an arm 42 extending outwardly of the turret from the lower head bracket 16. The two cooperating weld pocket member half-sections 39 are spring-loaded so as to be normally held [in their closed position abutting one another by the force of respective tension coil springs 43 connected to the said sections 39. The operating shafts are rotated, to effect the pivot-a1 opening and separating of the two weld pocket member half-sections 39, by the engagement of rollers 44 on the ends of arms 45 fastened on the lower ends of the shafts 40, with a cam-actuated lever (not shown) operated from the cam shaft of the machine.

In the opena-tion of the apparatus to make a glow lamp in accordance with the method of our invention, a pair of welds or leading-in wires and electrode assemblies 3, 4 and a glass tube 9 are inserted, at the respective weld loading and glass tube loading stations (not shown) of the machine, in the pockets 38 of the weld holder means 37 and in the tube holder jaws 10, 11 in proper position for sealing together as shown in FIG. 4. The so positioned glass tube 9 and the lead-in wire assemblies 3, 4 are then carried through a plurality of successive heating stations, as represented by the stations designated A,B, and C in FIG. 1, where an intermediate portion 46 of the glass tube 9, located just above the electrodes 4 therein, is heated to a plastic state, as shown in FIG. 4, by

gas fires 47 directed thereagainst from gas burners 48 located at the said stations, the said burners 48 being supported on gas burner manifolds 46' pivotally mounted on the machine frame, in accordance with conventional practice as shown, for example, in copending application Serial No. 465,535 of S. B. Simer, filed October 26, 1954, now Patent No. 2,876,591 issued March 10, 1959, so as to swing outwardly of the turret 6 out of the path of travel of the heads '7 during each index movement of of the turret.

During the subsequent index movement of each head 7 from stations C to D, the upper pair of tube-holding jaws 11 is moved upwardly relative to the lower pair of jaws it which remain in a fixed elevational position during such index movement, to thereby draw out and stretch the plastic intermediate section 46 of the glass tube 9 and form an attenuation or constriction 49 therein of antiplastic shape (i.e., concave longitudinally and convex iaterally), as shown in FIG. 5. The upward movement of the jaws ll to effect this drawing out and attenuation of the glass tube 9 is brought about by the roller 31 on the upper head bracket 2.4 engaging and riding up the rise portion 33 of the stationary cam track 34 during the index of the heads 7 from stations C to D. As shown in H6. 5, the attenuation or constriction 49 thus formed in the glass tube 9 is of relatively extended length characterized by a minimum diameter center region 56 and long, gradually flaring upper and lower end poi-- tions 51 and 52. All the operations performed thus far, as well as the apparatus described up to this point for performing such operations, are essentially the same as that conventionally performed and existing heretofore.

In accordance with the present invention, however, immediately upon completion of the glass tube attenuation operation as shown in FIG. 5, and while the glass of the constricted section 56 is still in a plastic state, the gradually diverging lower end portion 52 of the constric tion nearest the lower end portion of the glass tube 9 which is to ultimately form the envelope 1 of the glow lamp, is suitably reshaped or molded to further reduce the diameter thereof to a size (as shown at 53 in FIG. 8) approximately corresponding to that of the minimum dieter central region 56 of the constriction 49 and, in addition, form the lowermost end region of the constriction 59 into a short, Well-rounded shoulder 54 which ultimately serves as the top end of the lamp envelope 1. This reshaping or molding of the glass tube 9 is performed at station D of the illustrated apparatus by reshaping or molding mechanism 55 according to the invention, which mechanism is located at said station D and comprises a split mold 56 consisting of a pair of cooperating jawlike mold halves or sections 57 carried at the ends of jaw arms 53 which are pivotally mounted to swing the mold halves 57 in a horizontal plane so as to close around and encompass the constricted section 49 of the glass tube 9 while the tube is positioned at station D. The opposing faces of the mold halves 57 are formed with corresponding cavities or recesses 59 which, when the two mold halves are closed together, conjointly form a mold cavity 59 of the particular shape to which the tube constriction 4-9 is to be molded. Thus, as shown in H68. 6 and 7, the mold cavity 59 is composed of a short, wellrounded cup-shaped lower portion 66 which is adapted to mold the glass forming the lowermost portion 52 of the constriction 49 into a short well-rounded shoulder 54 on the glass tube 9, and a short tubular upper portion 61 which approximately corresponds in diameter to, but is preferably slightly larger than the smallest diameter central section 66 of the constriction 49, and is adapted to reduce the diameter of that portion of the constriction 49 immediately above the [rounded shoulder 54 to a size approximately corresponding to the smallest diameter central section 56 of the constriction 49.

As shown in FIG. 2, the mold supporting arms 58 are pivotally mounted to swing in a horizontal plane on vertical pivot pins 62 extending from a depending Vertical leg 63 of an L-shaped mounting bracket 64 which is pivoted at its upper end on a horizontal pivot pin 65 mounted on a vertically reciprocable slide 66, so as to swing in a vertical plane radially of the turret 6 to permit the said mounting bracket 64 and its associated molding mechanism 55 to be swung outwardly of the turret 6 out of the path of travel of each head 7 during the index thereof to and away from the glass tube reshaping station D. The slide 66 is vertically slida'ole in a guideway 67 formed in the face of a guide block 68 which is secured to a support bracket 69 fastened to a stationary portion 70 of the machine. The slide 66 is held in place within the guideway 67 by cover plates 71 fastened to the face of the guide block 66 and partly overlying the outer side of the slide 66. The slide 66 and the associated mounting bracket 64 and tube reshaping mold 56 are normally held in an upper position, as determined by the engagement of the upper end of the slide 66 with an upper stop screw 72 on the guide block 68, by the force of a tension coil spring 73 connected at one end to the slide 66 and at its other end to a spring post 74 extending from the guide block 63. The stop screw 72 is so adjusted as to position the tubular upper portion 61 of the mold cavity 59 in substantial horizontal alignment with the smallest diameter mid-portion 56 of the constriction 4.9 in the glass tube f9 when the slide 66 is held in abutting engagement with the stop screw 72 by the coil spring 73.

The mold supporting bracket 64 and the associated tube-reshaping mold 56 are normally held in an inward pivoted position about the pivot pin 65, in which position the mold cavity 59 of the mold 56, when closed, is in vertically centered alignment with the glass tube 9 held in the jaws 16 and H, by the force of a tension coil spring 75 connected at one end to the mounting bracket 64 and at its other end to the slide 66. The said inward pivoted operative position of the mounting bracket 64 and associated tube-reshaping mold 56 is determined by the engagement of a stop pin 76 on the mounting bracket 64- with the slide 66. Immediately before each index movement of the turret 6, the mounting bracket 64 and its associated tube-reshaping mold 56 are swung or tilted outwardly away from the turret so as to move the mold 56 out of the path of travel of the head 7 and the glass tube held therein during its index movement to the tube-reshaping station D, by the engagement of a pin 77 extending from the gas burner manifold 48' at said station with a roller '78 mounted on the depending leg 63 of the mounting bracket 6 the various gas manifolds 43 at such time being swung outwardly so as to be out of the path of travel of the heads 7 to the tube heating stations A to C and E to G.

The pivoted mold-carrying arms 58 (which are additionally supported by a supplementary support plate 79 fastened on the brackets 64 and through a slot in which plate the said arms extend) are spring-loaded, so as to be continually urged toward a closed position in which the two mold halves or jaws 57 are closed together around the glass tube by the force of respective tension coil springs 86 connected at their opposite ends to spring posts 81 and 82 extending from the arms 58 and mounting bracket 64, respectively. The said mold halves or jaws 57, however, are normally held in an open or separated position at all times, except during the dwell of each head 7 at the tube-reshaping station D, by means of a cylindrical type wedge cam 83 which is formed at the lower end of a spring-loaded vertically reciprocable cam actuating rod 84. The cam actuating rod 84 is vertically reciprocable within the horizontal leg 85 of the mounting bracket 64 and in a horizontal arm 86 extending from the vertical leg 63 of the said bracket 64 and it is normally held in a raised or upper limiting position, as determined by the engagement of a stop collar 87 on the rod $4 with the underside of the bracket leg 85, by the force of a pair of tension coil springs 36 which are connected at their opposite ends to spring posts 39 and 99 extending from the actuating rod 8d and the bracket leg 35, respectively. When the actuating rod is elevated to its raised or upper limiting position, the wider lower end portion of the wedge cam 83 engages between rollers 91 mounted on the mold-carrying ar 38 53 to thereby swing the said arms 58 and their associated mold halves or jaws 57 to, and hold them in, their open or separated position. When the cam actuating rod is moved downwardly in the mounting bracket 64 so as to displace the wider portion of the wedge cam 83 downwardly and out from between the rollers 91 on the mold-carrying arms 58, and position the narrower or reduced diameter portion 92 of the cam 83 between the rollers 91 instead, the mold-carrying arms 53 and the associated mold halves 57 are then free to be swung to their closed position around the glass tube 9 in the head 7 at station D by the action of the mold-closing springs 8d. The cam actuating rod 34 is moved downwardly to and held in its lowered position, to permit the closing of the split mold 56 by the springs 3%, by actuating mechanism 93 comprising a pivoted operating arm 94 which engages a roller 95 mounted on the top end of the cam-actuating rod 84 and is pivoted by a cam follower arm 96 (FIG. 3) which is connected by a vertical connecting rod 97 to the operating arm 94 and is actuated by a plate cam 98 on the main drive or cam shaft 8 of the apparatus. The cam follower arm 96 is pivoted at one end on a pivot shaft 59 and it is provided with a roller 1% which rides on the periphery or cam surface Hill of the plate cam 98 and is continuously held thereagainst by the force of a coil spring 132 connected to the other end of the cam follower arm 96. The operating arm 94 is pivotally mounted on a horizontally extending pivot shaft or pin 16 3 which is mounted on the support bracket 69 for the glass tube molding mechanism 55.

During the last portion of the downward movement of the cam actuating rod 84 by the operating arm 94, and after the closing of the split mold 56 around the glass tube 9 in the head 7, a stop collar 164 on the cam actuating rod abuts against the upper side of the horizontal leg 35' of the vertically movable mounting bracket 84 and moves the said bracket and the slide 66 on which it is supported bodily downward a slight distance as determined by the engagement of the lower end of slide 66 with an adjustable lower stop screw 1425 on the guide block 63. This sli ht downward movement of the slide 66 and associated bracket 64 then carries the split mold 536 a corresponding slight distance downwardly to its lowered position, as shown in FIGS. 2 and 7, to thereby reshape the plastic lower end portion 52 of the constriction 49 in the glass tube 9 so as to reduce the diameter thereof to a size as shown at 53 approximately corresponding to the smallest diameter mid-portion 53 of the tube constriction 49 and at the same time upset or mold the plastic glass at the lowermost end region of the constriction 49 into the form of a short well-rounded shoulder 54 on the tube which shoulder eventually constitutes the top end of the lamp envelope 1.

Upon completion of the downward movement of the mold 56 to effect the reshaping of the glass tube 9 at station D, and before the start of the next index movement of the turret, the split mold 56 is opened and returned to its elevated position, in readiness for the next cycle of operation thereof, by the upward movement of the cam actuating rod 84 to its elevated position. During the first part of the upward stroke of the cam actuating rod 84, the wedge cam 33 thereon operates to separate and swing the mold carrying arms 58 and the associated mold halves 57 to their open position so as to disengage from the glass tube 9. The mounting bracket 64- and the associated slide are held down in their lower position, however, during the first portion of the upward stroke of the cam actuating rod d4, ecause of the fact that the downward holding force exerted by the extended coil springs 83 on the mounting bracket 64 and slide 66 is greater than and overrides the upward lifting force of the coil spring 73 on the slide 66 and bracket 64.

When the lower stop collar 87 on the cam actuating rod 84- engages with the underside of the leg 85 of bracket 64- during the course of the further upward movement of the said rod 34, the downward holding force exerted by the coil springs 33 on the bracket 64 and associated slide 66 is then removed therefrom. As a result, the upward lifting force exerted by the coil spring 73 on the slide 66 then acts to raise the slide 66 associated bracket 64 and return them to their upper limiting position as determined by the e 'agement of the upper end of the slide 66 with the upper stop screw 72.

rile upward movement of the slide 66 and associated bracket 64 to their upper limiting posit on then raises the split mold 56 to its original elevated '1 position shown in PEG. 6, in readiness for the cycle of operation. Just before the start .5; index movement of the turret 6 to carry the next head 7 to the tube reshaping station D, the mounting bracket is pivoted or tilted outwardly of the turret about its pivot point 65, so as to swing the split mold 56 out of the path of index movement of the next head 7 and the glass tube 9 therein to the tube reshaping station D, by the engagement of the roller 73 on the lower end of the bracket 64 with the striker pin 77 on the gas burner manitold 48 which, at such time, is swung outwardly of the turret so as to also be out of the path of index movement of the heads 7. After the index of the next head '7 to the tube-reshaping station D, gas manifolds 48 and striker pin 77 then swing inwardly to the operative position of the gas burners 48 to heat the glass tubes 9 at the heating stations A, B and C, the inward swinging of the gas burner manifold 48 and striker pin 77 at the same time permitting the spring 75 to swing the mounting bracket 64 and the associated tube reshaping mechanism 55 inwardly to their operative position as determined by the engagement of the stop pin '76 with the slide 66.

Following the reshaping of the constricted portion 49 of the glass tube 9 at the reshaping station D, the assembly of the glass tube 9 and the lead-in wire and electrode assemblies 3, 4 in the head '7 is then carried through a series of heating stations as represented by the stations designated E, F and G in FIG. 1 where, as shown in FIG. 8, the lower end of the glass tube 9 is heated by gas fires 96 directed thereagainst from gas burners 107 at said stations to soften the glass at the said lower end of the tube. From the last heating station G, the head 7 then carries the heated glass tube 9 and the leading-in Wires 3 to a stem press forming station H where the plastic lower end of the glass tube 9 is pressed firmly around the lea ing-in wires 3, to form a flattened stem press 2 in which the leading-in wires are sealed, by the closing of a pair of press-forming jaws 103 at said station, as shown in FIGS. 1 and 9. The heating and pressing of the lower end of the glass tube 9 as thus described to form the stem press 2 is carried out in the same manner and by the same mechanism previously employed for such purpose.

The completed lamp envelope assembly 109 (FIG. 10) thus produced by the method and apparatus as disclosed herein is then removed from the head 7 of the apparatus at the unloading station thereof and, in accordance with usual lampmaking procedure, then placed in the exhaust head of a conventional type lamp exhaust, and if desired gas filling, machine where the glass tube 9 is then exhausted through the open end lid of the glass tube 9, a gas filling (when desired) then introduced into the glass tube through the said open end 110 thereof, and the constricted section 4-9 of the glass tube then tipped off at a region closely adjacent the rounded shoulder 54 on the tube, by directing sharp gas fires llll against the said region of the constriction, as shown in FIG. 10, to thereby hermetically seal the portion 1 of the glass tube constituting the envelope of the glow lamp and complete the manufacture thereof.

From the above it will be evident that we have provided an expeditious and inexpensive way, and apparatus oi simple form and entirely satisfactory in operation for manufacturing, directly on a lamp sealing machine, a tubular electric lamp or discharge device such as a glow lamp from a single piece of straight glass tubing so as to have a bulb formed with a short and preferably wellrounded top end more nearly approaching a squared top end, with a small centralized exhaust tip projecting therefrom. Because of the shortened top end of the lamp bulb and resulting considerable increase in the length of the straight side wall portion of the lamp bulb for the same overall length thereof, it is therefore possible to employ straight wire type glow lamp electrodes in the lamp bulb of appreciably greater length, for the same overall length of lamp bulb, than that possible in prior type glow lamp devices of this general type having the heretofore customary long, tapering top ends or stringy exhaust tips on the lamp bulb. Alternatively, by the use of our invention as described, it is possible to manufacture a glow lamp of appreciably shorter overall bulb length, for the same length of electrodes, than that possible heretofore with such prior type devices. Also, the formed and wellrounded short top end of the lamp bulb, with its small centralized exhaust tip, as produced by the lamp making procedure and apparatus according to our invention, presents a much neater and more finished appearance than the unsightly long and stringy exhaust tips prevalent with glow lamps of this general form as made heretofore.

Although a preferred embodiment of our invention has been disclosed, it will be understood that the invention is not to be limited to the specific construction and arrangernent of parts shown and to the specific procedures described, but that they may be widely modified within the spirit and scope of our invention as defined by the appended claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. The method of making an electric lamp or similar device of the type comprising a tubular glass envelope having lead-in wires sealed into an end thereof and an exhaust tip at its other end, which method comprises positioning the lead-in lwires within one end of an openended glass tube of uniform diameter throughout in position for sealing thereinto, heating to a plastic state and stretching an intermediate portion of the length of said glass tube to form the said tube portion into an extended longitudinally flaring constriction, upsetting the flaring end portion of said constricted section nearest the said one end of the tube, while the glass thereof is in a plastic condition, into a substantially cylindrical shaped section approximately corresponding in size to the diameter of the smallest diameter mid-portion of said constriction and terminating in a short shoulder on the tube, sealing the said lead-in wires into the said one end of the glass tube, and then evacuating the glass tube through its open other end and tipping-oil the constricted section thereof closely adjacent the said rounded shoulder.

2. The method or" making an electric lamp or similar device as specified in claim 1 wherein the said upsetting or the constricted portion of said glass tube is performed while the glass of the said constricted portion is still in a heated and plastic state from the said heating thereof for the said constricting operation.

3. The method of making a tabulated envelope assembly for an electric lamp or similar device of the type comprising a tubular glass envelope having lead-in wires sealed into an end thereof and carrying the internal elements or" the device, which method comprises positioning the lead-in wires within one end of an open-ended glass tube of uniform diameter throughout in position for sealing thereinto, heating to a plastic state and stretching an intermediate portion of the length of said glass tube to form an extended longitudinally flaring constriction in the tube, upsetting the flaring end portion of said constricted section nearest the said one end of the glass tube,

iii

while the glass thereof is in a heated and plastic condition, into a substantially cylindrical shaped section approximately corresponding in size to the diameter of and substantially concentric with the smallest diameter midportion of said constriction and terminating in a short shoulder on the tube, and then sealing the said lead-in wires into the said one end of the glass tube.

4. Apparatus for making tubular electric lamps or similar devices comprising a head having vertically spaced upper and lower jaws for holding a glass tube of uniform diameter throughout in a vertical position and a holder for supporting leading-in wires in a position extending into the open lower end of the tube held in said jaws for sealing therein-to, means for heating an intermediate portion of the length of said glass tube to a plastic condition, means for efiecting relative vertical displacement of said pairs of jaws to stretch the plastic intermediate portion of the glass tube and form a flaring constriction therein, a split mold comprising two mold halves located between the said pairs of jaws in a position to close around the said constriction in the glass tube, support means mounting said mold halves for unitary vertical movement and for horizontal movement toward and away from one another, spring means normally urging said mold halves together to close the split mold around the glass tube, and vertically reciprocable actuating means engageable on its upward stroke with said mold support means to open the split mold and engageable on its downward stroke with said support means to lower it so as to cause the mold to contract and upset the flaring lower portion of said constriction nearest the said end of the glass tube into a reduced diameter tubular portion terminating in a short shoulder on said tube, heating means mounted adjacent said lower jaws to heat the lower end of said glass tube to a plastic condition, and a pair of press jaws mounted adjacent said tube-holding jaws and operative to close against and compress the plastic lower end of the glass tube into a stem press.

5. Apparatus for making tubular electric lamps or similar devices comprising a head having vertically spaced upper and lower jaws for holding a glass tube of uniform diameter throughout in a vertical position and a holder for supporting leading-in wires in a position extending into the open lower end of the tube held in said jaws for sealing thereinto, means for heating an intermediate portion of the length of said glass tube to a plastic condition, means for effecting relative vertical displacement of said pairs of jaws to stretch the plastic intermediate portion of the glass tube and form a flaring constriction therein, a split mold comprising two mold halves located between the said pairs of jaws in a normal position to close around the narrower mid-portion of the said constriction in the glass tube, support means including separate support arms mounting said mold halves for unitary vertical movement axially of said glass tube, spring means normally urging said mold halves together to close the split mold around the glass tube, and vertically reciprocable actuating means wedgingly engageable on its upward stroke with said mold support arms to separate them and open the split mold and abuttingly engageable on its downward stroke with said support means to lower it so as to cause the mold to contract and reshape the flaring lower portion of said constriction into a reduced diameter tubular portion and upset the lowermost end region of said flaring portion into a short shoulder on the tube, heatin means mounted adjacent said lower jaws to heat the lower end of said glass tube to a plastic condition, and a pair of press jaws mounted adjacent said tube-holding jaws and operative to close against and compress the plastic lower end of the glass tube into a stem press.

6. Apparatus for making tubular electric lamps or similar devices comprising a head having vertically spaced upper and lower jaws for holding a glass tube of uniform diameter throughout in a vertical position and a holder for supporting leading-in wires in a position extending into the open lower end of the tube held in said jaws for sealing thereinto, means for heating an intermediate portion of the length of said glass tube to a plastic condition, means for effecting relative vertical displacement of said pairs of jaws to stretch the plastic intermediate portion of the glass tube and form a flaring constriction therein, a split mold comprising two mold halves located between the said pairs of jaws in a position to close around the said constriction in the glass tube, said mold halves being carried by support arms horizontally movable toward and away from one another, vertically reciprocable support means mounting said support arms for unitary vertical reciprocating movement, the spring means connected to and normally urging said mold support arms horizontally toward one another to close the said mold halves together around the glass tube, actuating means comprising a vertically reciprocable actuating rod extending between and having a wedge cam portion engageable in the up position of said rod with the said mold support arms to separate them and open the said mold against the closing force of said spring means, said actuating rod initially disengaging its said wedge cam portion from between said support arms on its downward stroke to permit the closure of said mold halves around the glass tube by the said spring means, the actuating rod engaging the said support means during the latter portion of its downward stroke to move the then closed mold downwardly to cause it to contract and reshape the flaring lower portion, of said constriction nearest the said end of the glass tube into a reduced diameter cylindrical portion terminating in a short shoulder on said tube, heating means mounted adjacent said lower jaws to heat the lower end of said glass tube to a plastic condition, and a pair of press jaws mounted adjacent said tube-holding jaws and operative to close against and compress the plastic lower end of the glass tube into a stem press.

7. Apparatus for making tubular electric lamps or similar devices comprising a head having vertically spaced upper and lower jaws for holding a glass tube of uniform diameter throughout in a vertical position and a holder for supporting leading-in wires in a position extending into the open lower end of the tube held in said jaws for sealing thereinto, means for heating an intermediate portion of the length of said glass tube to a plastic condition, means for effecting relative vertical displacement of said pairs of jaws to stretch the plastic intermediate portion of the glass tube and form a flaring constriction therein, a split mold comprising two mold halves located between the said pairs of jaws in a position to close around the said constriction in the glass tube, support means for said split mold comprising a vertically reciprocable support bracket and a pair of support arms pivoted at one end on said bracket for horizontal pivotal movement and each carrying a respective one of said mold halves at their other end, spring means connected to and normally holding said support means in a raised position to locate the said mold halves at an elevation to close around the narrower mid-portion of the said constriction, other spring means connected between and normally urging said pivoted support arms toward one another to close the said mold halves together around the glass tube, a springloaded vertical actuating rod vertically reciprocable in said support bracket and extending between said support arms and provided with a wedge cam portion engageable, in the spring-held raised position of said rod, with the said support arms to separate them and open the said mold against the closing force of said other spring means, said actuating rod disengaging its said wedge cam portion from between said support arms during the first part of its downward stroke from its said raised position and abuttingly engaging said support bracket during the latter part of its downward stroke to move the mold support means and the then closed mold downwardly to cause the mold to contract and reshape the flaring lower portion of the said constriction in the glass tube into a reduced diameter cylindrical portion and upset it into a short rounded shoulder on the tube, heating means mounted adjacent said lower jaws to heat the lower end of said glass tube to a plastic condition, and a pair of press jaws mounted adjacent said tube-holding jaws and operative to close against and compress the plastic lower end of the glass tube into a stern press.

References Cited in the file of this patent UNITED STATES PATENTS 1,722,161 Strickland July 23, 1929 1,736,766 Burrows Nov. 19, 1929 1,736,767 Burrows Nov. 19, 1929 2,053,318 Blackburn Sept. 8, 1936 2,087,947 Dichter July 27, 1937 2,101,213 Dichter Dec. 7, 1937 2,235,515 Carpenter Mar. 18, 1941 2,321,224 Madden et al. June 8, 1943 2,324,237 Reichel July 13, 1943 2,491,237 Way Dec. 13, 1949 2,836,011 Hutchins May 27, 1958 2,845,325 Seitz July 29, 1958 FOREIGN PATENTS 46,279 France June 3, 1935 

1. THE METHOD OF MAKING AN ELECTRIC LAMP OR SIMILAR DEVICE OF THE TYPE COMPRISING A TUBULAR GLASS ENVELOPE HAVING LEAD-IN WIRES SEALED INTO AN END THEREOF AND AN EXHAUST TIP AT ITS OTHER END, WHICH METHOD COMPRISES POSITIONING THE LEAD-IN WIRES WITHIN ONE END OF AN OPENENDED GLASS TUBE OF UNIFORM DIAMETER THROUGHOUT IN POSITION FOR SEALING THEREINTO, HEATING TO A PLASTIC STATE AND STRETCHING AN INTERMEDIATE PORTION OF THE LENGTH OF SAID GLASS TUBE TO FORM THE SAID TUBE PORTION INTO AN EXTENDED LONGITUDINALLY FLARING CONSTRICTION, UPSETTING THE FLARING END PORTION OF SAID CONSTRICTED SECTION NEAREST THE SAID ONE END OF THE TUBE, WHILE THE GLASS THEREOF IS IN A PLASTIC CONDITION, INTO A SUBSTANTIALLY CYLINDRICAL SHAPED SECTION APPROXIMATELY CORRESPONDING IN SIZE TO THE DIAMETER OF THE SMALLEST DIAMETER MID-PORTION OF SAID CONSTRICTION AND TERMINATING IN A SHORT SHOULDER ON THE TUBE, SEALING THE SAID LEAD-IN WIRES INTO THE SAID ONE END OF THE GLASS TUBE, AND THEN EVACUATING THE GLASS TUBE THROUGH ITS OPEN OTHER END AND TIPPING-OFF THE CONSTRICTED SECTION THEREOF CLOSELY ADJACENT THE SAID ROUNDED SHOULDER.
 5. APPARATUS FOR MAKING TUBULAR ELECTRIC LAMPS OR SIMILAR DEVICES COMPRISING A HEAD HAVING VERTICALLY SPACED UPPER AND LOWER JAWS FOR HOLDING A GLASS TUBE OF UNIFORM DIAMETER THROUGHOUT IN A VERTICAL POSITION AND A HOLDER FOR SUPPORTING LEADING-IN WIRES IN POSITION EXTENDING INTO THE OPEN LOWER END OF THE TUBE HELD IN SAID JAWS FOR SEALING THEREINTO, MEANS FOR HEATING AN INTERMEDIATE PORTION OF THE LENGTH OF SAID GLASS TUBE TO A PLASTIC CONDITION, MEANS FOR EFECTING RELATIVE VERTICAL DISPLACEMENT OF SAID PAIRS OF JAWS TO STRETCH THE PLASTIC INERMEDIATE PORTION OF THE GLASS TUBE AND FORM A FLARING CONSTRICTION THEREIN, A SPLIT MOLD COMPRISING TWO MOLD HALVES LOCATED BETWEEN THE SAID PAIRS OF JAWS IN A NORMAL POSITION TO CLOSE AROUND THE NARROWER MID-PORTION OF THE SAID CONSTRICTION IN THE GLASS TUBE, SUPPORT MEANS INCLUDING SEPARTE SUPPORT ARMS MOUNTING SAID MOLD HALVES FOR UNITARY VERTICAL MOVEMENT AXIALLY OF SAID GLASS TUBE, SPRING MEANS NORMALLY URGING SAID MOLD HALVES TOGETHER TO CLOSE THE SPLIT MOLD AROUND THE GLASS TUBE, AND VERTICALLY RECIPROCABLE ACTUATING MEANS WEDGINGLY ENGAGEABLE ON ITS UPWARD STROKE WITH SAID MOLD SUPPORT ARMS TO SEPARATE THEM AND OPEN THE SPLIT MOLD AND ABUTTINGLY ENGAGEABLE ON ITS DOWNWARD STROKE WITH SAID SUPPORT MEANS TO LOWER IT SO AS TO CAUSE THE MOLD TO CONTRACT AND RESHAPE THE FLARING LOWER PORTION OF SAID CONSTRICTION INTO A REDUCED DIAMETER TUBULAR PORTION AND UPSET THE LOWERMOST END REGION OF SAID FLARING PORTION INTO A SHORT SHOULDER ON THE TUBE, HEATING MEANS MOUNTED ADJACENT SAID LOWER JAWS TO HEAT THE LOWER END OF SAID GLASS TUBE TO A PLASTIC CONDITION, AND A PAIR OF PRESS JAWS MOUNTED ADJACENT SAID TUBE-HOLDING JAWS AND OPERATIVE TO CLOSE AGAINST AND COMPRESS THE PLASTIC LOWER END OF THE GLASS TUBE INTO A STEM PRESS. 